How to replace curl data-binary value to form-data upload parameters

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TL;DR

In this post I will explain how master Joda visited me in my dream and asked me important question about one of my previous blog posts: How to measure upload speed of web application upload form [link]. The post provided right information about curl parameter that enables you to see upload speed. But curl example for upload file is wrong!

I found that is wrong when I tried to measure upload speed in real application. And realized that file is not uploaded in application. By observing the copy pasted curl, I noticed that there was not Content-Length header. Bingo, lets create Chrome developer tools issue ticket[link].

Please read comments, because I learned a lot about curl upload file feature. Google developers who answered my ticket did not just dismissed my wrong curl upload file heuristic, they took extra step and educated me!

So, in order to use curl upload file feature, you need to transform something like this:

--data-binary $'------WebKitFormBoundaryoeJQRnHeojsIBayU\r\nContent-Disposition: form-data; name="fileType"\r\n\r\n5\r\n------WebKitFormBoundaryoeJQRnHeojsIBayU\r\nContent-Disposition: form-data; name="file"; filename="elixir-websetup.exe"\r\nContent-Type: application/x-msdownload\r\n\r\n\r\n------WebKitFormBoundaryoeJQRnHeojsIBayU--\r\n'

into this:

-F file=@elixir-websetup.exe -F fileType=5

You can now data-binary parameter and its value from curl.

It is important to have check mechanism for upload file. Use your application features to check is file really uploaded. curl can also help by observing application returned value.

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